One tactic I found works well is to actually position the artwork where I
want it on the wall, then hold the top edge out a bit and put the hotmelt on
the back of the artwork first, then push it back in place. Repeat with the
bottom, which it easier because you'll have a free hand then. Doing it this
way allows the glue to cool just a bit before it gets to the wall, so the
bond there isn't quite so strong. But it is strong enough so that NONE of
the 600 pieces came off the wall all week without being invited -even though
it is a very high traffic hallway.